Chair control for synchronized movement of chair seat and back, and chair having same

ABSTRACT

A chair seat adjustment mechanism has a support, a back bracket for attachment to a chair back and a seat plate for attachment to a chair seat. The back bracket is pivotally mounted to the support at a first pivot. The seat plate, which extends above the support, is pivotally mounted to the back bracket at a second pivot and slidably hinged to the support at a third pivot. The second pivot is positioned above and rearwardly of the first pivot. The third pivot is positioned forwardly of the second pivot such that rearward titling of the back bracket draws the seat plate rearwardly and tilts a rear of the seat plate downwardly. The third pivot may be a pivot pin on the support slidably received in an elongate slot on the seat plate, which may be slightly declined towards the back. A chair having such a chair seat adjustment mechanism is more comfortable for some users.

FIELD OF THE INVENTION

The present invention relates to chair control mechanisms, particularlyto chair seat adjustment mechanisms for synchronized movements of chairseat and chair back, and chairs having the same.

BACKGROUND

Office chairs often allow for titling of the chair back. It has beenfound that, for many users, it is more comfortable if the seat positionis adjusted in synchronization with the back tilt. For example, thereare office chairs where the seat tilts and/or shifts forwardly when theback is tilted rearwardly.

However, some users may find it uncomfortable if the seat tiltsforwardly or shifts forwardly when the back is tilted. Further, somechair seat control mechanisms are relatively complex.

Therefore, there is a need for a simple chair control that allowssynchronized movement of the chair seat and the chair back. There isalso a need for a chair control that allows synchronized movement of thechair seat with the chair back, which may be more comfortable for users.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, there is provideda chair seat adjustment mechanism, comprising: a support; a back bracketfor attachment to a chair back, said back bracket pivotally mounted tosaid support at a first pivot; a seat plate extending above saidsupport, said seat plate for attachment to a chair seat, said seat platepivotally mounted to said back bracket at a second pivot and slidablyhinged to said support at a third pivot, said second pivot positionedabove and rearwardly of said first pivot and said third pivot positionedforwardly of said second pivot such that rearward titling of said backbracket draws said seat plate rearwardly and tilts a rear of said seatplate downwardly.

In accordance with further aspect of the present invention, there isprovided a chair comprising: a seat; a back; a support; a back bracketattached to said back, said back bracket pivotally mounted to saidsupport at a first pivot; and a seat plate attached to said seat andextending above said support, said seat plate pivotally mounted to saidback bracket at a second pivot and slidably hinged to said support at athird pivot, said second pivot positioned above and rearwardly of saidfirst pivot and said third pivot positioned forwardly of said secondpivot such that rearward titling of said back draws said seat rearwardlyand tilts a rear of said seat downwardly.

In accordance with another aspect of the present invention, there isprovided a chair seat adjustment mechanism, comprising: support meansfor supporting a chair seat and a chair back; first attachment means forattaching to said chair back, said first attachment means pivotallymounted to said support means at a first pivot means; and secondattachment means for attaching to said chair seat, said secondattachment means extending above said support means, said secondattachment means pivotally mounted to said first attachment means at asecond pivot means and slidably hinged to said support means at a thirdpivot means, said second pivot means positioned above and rearwardly ofsaid first pivot means and said third pivot means positioned forwardlyof said second pivot means such that rearward titling of said firstattachment means draws said second attachment means rearwardly and tiltsa rear of said second attachment means downwardly.

In accordance with yet another aspect of the present invention, there isprovided a chair seat adjustment mechanism, comprising: a support; aback bracket for attachment to a chair back, said back bracket pivotallymounted to said support at a first pivot; a seat plate extending abovesaid support, said seat plate for attachment to a chair seat, said seatplate pivotally mounted to said back bracket at a second pivot andslidably hinged to said support at a third pivot, said second pivotpositioned above said first pivot and either forwardly or rearwardly ofboth of said first and third pivots such that rearward titling of saidback bracket draws said seat plate rearwardly and tilts said seat platerearwardly.

Other aspects and features of the present invention will become apparentto those of ordinary skill in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In the figures illustrating example embodiments of the invention,

FIG. 1 is a side elevation of a chair having a chair control;

FIGS. 2A and 2B are side elevations of a portion of the chair of FIG. 1showing the chair control in two different positions;

FIG. 3 is a perspective view of the chair control of FIG. 1 inisolation;

FIGS. 4A and 4B are side elevations of an isolated component of thechair control of FIGS. 2A and 2B;

FIG. 5 is a diagram illustrating an alternative arrangement of thepivots; and

FIG. 6 is a diagram illustrating a further alternative arrangement ofthe pivots.

DETAILED DESCRIPTION

Referring to FIG. 1, an exemplary embodiment of an aspect of theinvention is a chair 10 having a chair control 12, which joins a chairseat 14 and a chair back 16 to a chair post 18. The post 18 may beadjustable in height. The chair control 12 may be supported by a singlepost, such as illustrated in FIG. 1, or by multiple posts or anothersuitable form of support.

Referring to FIGS. 2A and 2B, the chair back 16 can be tilted between aforward position (FIG. 2A) and a backward position (FIG. 2B). The chairseat 14 moves in synchronization with the tilting of the chair back 16so as to tilt and shift rearwardly when the chair back is titledrearwardly. The movements of the chair seat 14 are controlled by chaircontrol 12.

Referring to FIG. 3, the chair control 12, which is an exemplaryembodiment of the invention, has a support, such as main frame 20,mountable to the post 18 for supporting the chair seat 14 and the chairback 16, a seat plate 24 for attachment to the chair seat 14, and a backbracket 26 for attachment to the chair back 16. The main frame 20 maydefine a cavity 22, which may conveniently accommodate variouscomponents of the chair control mechanism. Each of the seat plate 14 andback bracket 16 can be a channel-shaped bracket. One or both the seatplate 14 and back bracket 16 may, however, have other suitable shapes.

The back bracket 26 is pivotally mounted at a pivot 28 to the main frame20. The seat plate 24 extends above the main frame 20 and is pivotallymounted at a pivot 30 to the back bracket 26. The main frame 20 has apivot pin 32 and the seat plate 24 has an elongate slot 34. The elongateslot 34 of the seat plate 24 slidably receives the pivot pin 32 so thatthe seat plate 24 is slidably hinged to the main frame 20 at the pivot32. The slot 34 declines slightly from front to back. In an alternativeembodiment, an elongate slot may be formed on the main frame 20 insteadof the seat plate 24 and the seat plate may have a pivot pin received inthe slot on the main frame so that the seat plate 24 is slidably hingedto the main frame 20 at the pivot pin. The seat plate 24 may also beotherwise slidably hinged at the pivot 32 to the main frame 20.

Each of the pivot pins 36, 38, 40 is separately formed and inserted intothe openings in the corresponding component. Alternatively, the pins maybe integrally formed on the corresponding components.

The pivot 30 is positioned above and rearwardly of the pivot 28, and thepivot 32 is positioned forwardly of the pivot 30, such that rearwardtilting of the back bracket 26 draws the seat plate 24 rearwardly andtilts a rear of the seat plate 24 downwardly.

As is conventional, the back bracket 16 may be normally biased towardsthe forward position. For example, as illustrated in FIG. 3, the backbracket 26 may be biased by a coil spring 42 mounted in the cavity 22,which urges the back bracket to pivot forwardly.

As will be apparent from FIGS. 4A and 4B, pivotal movement of the backbracket 26 (FIG. 3) about the pivot 28 from a forward upright positionto a backward titled position will cause the seat plate 24 to shiftrearwardly, relative to the main frame 20, or pivot 28. The seat plate24 is also caused to tilt backwardly. For example, when the back bracket26 (FIG. 3) is tilted back from the position shown in FIG. 4A, it pivotsclockwise about pivot 28 and draws pivot 30 downwardly and rearwardly inthe direction of the arrow shown. As the pivot 30 moves downwardly andrearwardly, it draws the seat plate 24 rearwardly and the rear of theseat plate 24 at the pivot 30 downwardly. Since the seat plate 24 isslidably hinged at the pivot 32, it is able to shift rearwardly (in thedirection indicated by the top arrow in FIG. 4B) as the slot 34 slidesalong the pivot 32. A rear of the seat plate 24 is also able to tiltdownwardly as the seat plate 24 pivots about the pivot 32 in a clockwisedirection (as indicated by the arrow adjacent the pivot 30 in FIG. 4B).Consequently, the seat plate 24 moves towards the position shown in FIG.4B. Thus, rearward tilting of the back bracket 26 draws the seat plate24 rearwardly and tilts the rear of the seat plate 24 downwardly. Areverse pivotal movement of the back bracket 26 will cause reversemovement of the seat plate 24.

Therefore, the chair control 12 provides a chair seat adjustmentmechanism for adjusting the position of the chair seat 14 in response tothe tilting of the chair back 16.

The chair control 12 may also have a locking mechanism (not shown) forselectively locking the back bracket 26 in one of a plurality ofpositions. Such locking mechanisms are known to persons skilled in theart.

In use, the seat 14 is attached to the seat plate 24 and the chair back16 is attached to the back bracket 26. When the user tilts the back 16and hence the back bracket 26 backwardly, the seat plate 24 and hencethe chair seat 14 will shift and tilt rearwardly. When the chair back 16and hence the back bracket 26 is titled forwardly, the seat plate 24 andhence the chair seat 14 will shift and tilt forwardly.

Thus, the chair 10 is comfortable to use for users who prefer suchsynchronized movement of the chair seat 14 and the chair back 16.

In contrast, if the pivots 28, 30 and 32 are arranged such that thepivot 30 is between the pivots 28 and 32, a pivotal movement of the backbracket 26 would cause a tilting of the seat plate 24 in the oppositedirection. That is, when the back bracket 26 pivots backwardly, the seatplate 24 shifts rearwardly but pivots forwardly, and when the backbracket 26 pivots forwardly, the seat plate 24 shifts forwardly butpivots backwardly.

Another advantage of the chair control 12 is that the distance betweenpivots 30 and 32, or pivot 28 and the chair back 16, may be maximizedfor a given overall size of the chair control 12, if so desired. Thus,the chair control 12 can have a compact size with good functionality anddurability. For example, a longer distance between the pivots may reducethe torque required to actuate the control, and thus the stress on thecomponents.

The chair control 12 is also simple in construction. It only requirestwo moving components to function, namely the seat plate and the backbracket.

As now can be appreciated, it is possible to alter the movement of thechair seat 14 in response to the titling of the chair back 16 byadjusting relative positions of the pivots 28, 30 and 32. Alternatively,it is possible to alter the degree of tilt of the seat by adjusting theshape and orientation of the slot 34. For example, a steep decline ofthe slot 34 may reduce the amount of tilting of the seat 14 when theback 16 is tilted. As will be understood by a person skilled in the art,when the slot 34 declines from front to back, the amount of tilting ofthe seat plate 24 is reduced because the vertical distance betweenpivots 30 and 32 changes less when the back bracket 26 is pivoted aboutpivot 28, compared with a leveled slot. Further, the slot 34 may becurved so that pivot 32 can follow more closely the arcuate movement ofthe pivot 30 so as to reduce or eliminate tilting of the seat plate 24caused by the pivotal movement of the back bracket 26. When the slotdeclines from back to front, the amount of titling of the seat plate 24is increased in comparison to a leveled slot.

Further, when the pivot 30 is nearly directly above the pivot 28,titling of the back bracket 26 causes more horizontal shift thandownward tilt of the seat plate 24. In contrast, when the pivot 30 isrearwardly remote from the pivot 28, titling of the back bracket 26causes more downward tilt than horizontal shift of the seat plate 24.

As can be understood by one of skill in the art, in an alternativeembodiment the pivot 32 may be positioned between the pivots 28 and 32as shown in FIG. 5. In such an arrangement, rearward tilting of the backbracket 26 also draws the seat plate 24 rearwardly and tilts the rear ofthe seat plate 24 downwardly.

The pivots may also be positioned as shown in FIG. 6. In this case, thepivot 30 is positioned above the pivot 28 and forwardly of both of thepivots 28 and 32. The relative positions of the pivots 28 and 30 mayvary, as discussed above. As can be appreciated, under this arrangement,rearward tilting of the back bracket again draws the seat platerearwardly but tilts the front of the seat plate upwardly. However,since the pivots 28 and 32 are on the same side of the pivot 30, theseat plate is again tilted clockwise. Some users may prefer this kind ofseat movement when the back is tilted backwardly.

In the exemplary embodiments described above and illustrated in thefigures, the seat plate 24 and the back bracket 26 are bothchannel-shaped and are nested with each other and the main frame 20.While channel-shaped brackets are advantageous as the control assemblycan be made compact and to accommodate other components whilemaintaining good physical strength, the seat plate or the back bracketmay be otherwise shaped.

The chair control 12 may incorporate any other suitable components orcontrol mechanisms for adjusting the chair height, chair seat, or chairback. For example, the chair control 12 may include handles foradjusting or locking any of the components of the chair, biasing membersfor biasing a part of the control, actuators for actuating an adjustmentsuch as a gas cylinder actuator, and the like.

Other features, benefits and advantages of the present invention can beunderstood from this description and the drawings by those skilled inthe art.

Of course, the above described embodiments are intended to beillustrative only and in no way limiting. The described embodiments aresusceptible to many modifications of form, arrangement of parts, detailsand order of operation. The invention, rather, is intended to encompassall such modification within its scope, as defined by the claims.

1. A chair seat adjustment mechanism, comprising: a support; a backbracket for attachment to a chair back, said back bracket pivotallymounted to said support at a first pivot; a seat plate extending abovesaid support, said seat plate for attachment to a chair seat, said seatplate pivotally mounted to said back bracket at a second pivot andslidably hinged to said support at a third pivot, said second pivotpositioned above and rearwardly of said first pivot and said third pivotpositioned forwardly of said second pivot such that rearward titling ofsaid back bracket draws said seat plate rearwardly and tilts a rear ofsaid seat plate downwardly.
 2. The mechanism of claim 1, wherein one ofsaid seat plate and said support defines an elongate slot, and whereinsaid third pivot comprises a pivot pin on the other of said seat plateand said support slidably received in said slot, such that said seatplate is slidably hinged at said pivot pin.
 3. The mechanism of claim 2,wherein said slot is shaped and oriented to allow reciprocal movement ofsaid seat plate when said back bracket is pivoted about said firstpivot.
 4. The mechanism of claim 1, wherein said back bracket isnormally biased towards a forward position.
 5. The mechanism of claim 1,wherein at least one of said seat plate and said back bracket isgenerally channel-shaped and is nested with said support.
 6. A chaircomprising: a seat; a back; a support; a back bracket attached to saidback, said back bracket pivotally mounted to said support at a firstpivot; and a seat plate attached to said seat and extending above saidsupport, said seat plate pivotally mounted to said back bracket at asecond pivot and slidably hinged to said support at a third pivot, saidsecond pivot positioned above and rearwardly of said first pivot andsaid third pivot positioned forwardly of said second pivot such thatrearward titling of said back draws said seat rearwardly and tilts arear of said seat downwardly.
 7. The chair of claim 6, wherein one ofsaid seat plate and said support defines an elongate slot, and whereinsaid third pivot comprises a pivot pin on the other of said seat plateand said support slidably received in said slot, such that said seatplate is slidably hinged at said pivot pin.
 8. The chair of claim 7,wherein said slot is shaped and oriented to allow reciprocal movement ofsaid seat plate when said back bracket is pivoted about said firstpivot.
 9. The chair of claim 8, wherein said back bracket is normallybiased towards a forward position.
 10. The chair of claim 6, wherein atleast one of said seat plate and said back bracket is generallychannel-shaped and is nested with said support.
 11. A chair seatadjustment mechanism, comprising: support means for supporting a chairseat and a chair back; first attachment means for attaching to saidchair back, said first attachment means pivotally mounted to saidsupport means at a first pivot means; and second attachment means forattaching to said chair seat, said second attachment means extendingabove said support means, said second attachment means pivotally mountedto said first attachment means at a second pivot means and slidablyhinged to said support means at a third pivot means, said second pivotmeans positioned above and rearwardly of said first pivot means and saidthird pivot means positioned forwardly of said second pivot means suchthat rearward titling of said first attachment means draws said secondattachment means rearwardly and tilts a rear of said second attachmentmeans downwardly.
 12. A chair seat adjustment mechanism, comprising: asupport; a back bracket for attachment to a chair back, said backbracket pivotally mounted to said support at a first pivot; a seat plateextending above said support, said seat plate for attachment to a chairseat, said seat plate pivotally mounted to said back bracket at a secondpivot and slidably hinged to said support at a third pivot, said secondpivot positioned above said first pivot and either forwardly orrearwardly of both of said first and third pivots such that rearwardtitling of said back bracket draws said seat plate rearwardly and tiltssaid seat plate rearwardly.